Backpack



FIG. 1 is a front perspective view of the first embodiment of a backpack comprising the present invention;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

Broken lines on claimed surfaces depict stitching and form no part of the claim. All other broken lines depict portions of the backpack, and form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 